I am having an issue with my bicycle. Over the last week or so, when coasting I can intermittently feel a rumbling/strong vibration in the pedals. Also, when I try to backpedal, I get a weird noise and there is some resistance.

As I say, the issue is intermittent - it happens frequently when I'm coasting but is not constant.

I recently had my internal gear hub (Sturmey Archer 3-speed) serviced and I'm wondering if something has gone awry following the servicing...

I am wondering if anyone might have any ideas or suggestions about what the issue could be and what can be done to rectify it.